updated 11:32 am EDT, Fri September 20, 2013

Shoppers find many models unavailable

Apple CEO Tim Cook made a surprise appearance this morning at the new Palo Alto Apple Store in California, accounts say. As some 200 or more people waited in line to buy new iPhones, Cook is said to have spoken with people in line and shook their hands. Palo Alto is roughly a 15-25 minute drive from Apple's headquarters in Cupertino.

Even as Cook met with prospective iPhone buyers, people were complaining about the lack of iPhone 5s stock on Twitter. "apple palo alto university out of gold - all carriers. Out of white - AT&T. And Tim Cook just walked by!", one person wrote. "Tim Cook visits hundreds of disappointed Apple fans at the Apple Store in Palo Alto," the caption for a Twitter photo reads.

Cook's presence is presumably a simple way to drum up publicity for the launch of both the iPhone 5s and 5c. The 5s is already in limited supply, and very few of the units available are in colors other than space gray.